1. Field of the Invention
The present invention relates to an internal combustion engine suitable for many uses including motor vehicles, aircraft, boats, etc., and which can provide high efficiency over a large range of power outputs.
2. Prior Art
Internal combustion engines used in vehicles and in boats are required to produce a wide range of power outputs. For example, an automobile operating at high speed, or on hills, may need 10 to 15 times the power required when driving on level city streets. It is not possible to design a conventional engine that has high efficiency over such a wide power range.
There have been suggestions, for example in U.S. Pat. No. 5,398,508, issued Mar. 21, 1995 to Brown, and in patents cited in the Brown patent, for motor vehicles to be provided with an auxiliary or booster engine to increase the power when needed. These auxiliary or booster engines have been separate from the main engine, having a separate crankshaft, which requires clutches or like means to temporarily connect the auxiliary engine to the main engine. Clutches or the like are an undesirable complication, especially if it is desired to continually switch from low power to high power, as will be needed when driving up and down hills. Also, the range of power given by these known arrangements is rather limited.
U.S. Pat. No. 5,701,062, which issued Dec. 23, 1997 to Barrett, refers primarily to problems with electrically driven vehicles, and suggests the use of multiple motors in a binary array, in which each motor has double the power of the next smaller motor, so that a series of motors of 1, 2, 4, 8, and 16 HP may be used. Although this patent has occasional references to "gas engines", these references are all in relation to separate engines, for example one engine driving the front wheels and another the rear wheels, which involve the same problems with clutch or like transmission elements as in the Brown patent.
Neither of these patents suggests a single internal combustion engine having a widely variable power output and which is arranged to avoid possible problems with transmission elements such as clutches.
So-called variable displacement engines have also been designed which are based on conventional engines having cylinders acting on a single crankshaft, and in which some cylinders can be deactivated to reduce the power. Such engines are described for example in U.S. Pat. No. 5,813,383 which issued Sep. 29, 1998 to Cummings. Since these engines are based on conventional engines with cylinders of uniform size, if they were to be designed to provide optimum efficiency over a really wide range of power outputs, for example 10 to 1 or 15 to 1, a large number of cylinders would be required.